Domestic water treatment devices are know in the art. Among these devices are self-contained systems which process water in batches. Examples of batch devices are pitchers/carafes and larger dispensers from which treated water is poured through a spigot. These systems typically have upper and lower chambers separated by a filter cartridge. They are called "pour-through" devices because they rely on gravity to force water from the upper chamber, through the cartridge, and into the lower chamber, thereby producing treated water.
As a result of recent improvements in filter media for pour-through devices, biological contaminants such as protozoan cysts (e.g., cryptosporidium) can now be removed. Successful removal of biological contaminants by the filter cartridge is of no benefit, however, if the treated water becomes contaminated with untreated water. Any contamination is unacceptable because even a small amount of biological contaminant would make all of the treated water unsuitable for drinking.
There are a number of ways that treated water can become contaminated with untreated water in a pour-through device. One way is if there is not an adequate seal between the filter and pour tray. Previously known sealing arrangements have generally involved a radial compression seal created simply by pushing the filter cartridge downwardly into the bottom of the pour tray. This approach provides no ready indication to the user, however, that a seal with good integrity has been achieved.
In carafes, another source of contamination is when pouring treated water out of the carafe. Some untreated water often remains in the pour tray, which can spill out when the carafe is tilted for pouring. If this is not prevented, untreated water from the pour tray can either mix with the treated water coming out of the carafe spout or leak around the pour tray and into the treated water remaining in the carafe.
Users also typically fill carafes by first turning on the faucet and then moving the carafe under it to fill the pour tray. As the edge of the carafe passes under the water stream, untreated water can leak between the top edges of the carafe and pour tray and into the bottom of the carafe. Untreated water can also splash into the pour spout when the pour tray is being filled.
What has been needed are better arrangements for separating treated water from untreated water in pour-through water treatment devices.